1. Field of the Invention
The present invention relates to a machine translation system for translating an original document presented in a first language into a translated document in a second language automatically.
2. Description of the Background Art
Generally speaking, a machine translation system obtains a translation in a second language of an original document in a first language by first segmenting the original document into a processing unit such as a word or a phrase by means of a morphological analysis and a syntactic analysis, then a semantic analysis is applied to each processing unit and an appropriate translation for each processing unit is searched through a translation dictionary, and then a proper translated document is obtained by combining the translation of each processing unit according to a prescribed translation grammar.
However, in a conventional machine translation system, it has been difficult to obtain a truly appropriate translation consistently, because of an immaturity of a technique of sentence structure and semantic analysis of a natural language.
Moreover, in general it is preferable to have similar interpretations for similar parts in the same document, but different interpretations for similar parts in the same document have often been obtained conventionally, depending on a context of each part.
For example, in translating an English document containing the following two sentences:
(1) "You have this paper." PA1 (2) "I wrote the paper."
into Japanese, assuming that for a translation of a word "paper" there are two candidates " " (pronounced "kami", meaning a sheet of a material to write or print on) and " " (pronounced "ronbun", meaning a dissertation), both of these candidates can be considered appropriate for the sentence (1). However, for the sentence (2), only a candidate " (dissertation)" can be considered appropriate.
For the case of the sentence (2), even conventionally, the proper candidate can be selected for the word "paper" from a requirement of consistency of this word with another word "wrote" in the same sentence. However, conventionally, for the case like that of the sentence (1), a selection of a proper candidate cannot be made from such a requirement of consistency within a sentence itself alone, so that an uncertainty of a translation inevitably arose.